1. Field of the Invention
The present invention relates to projection display systems, and more particularly, to a laser display system that uses a laser as a light source.
2. Background of the Related Art
Though a lamp has been used as a light source of a projection display system, recently, a laser display system is under development in which a laser is used in place of the lamp. The laser display system has advantages in that a clear picture can be provided since colors of a picture are clear, and close to pure colors, a range of reproduction of the colors is wide, and contrast of the picture is high.
FIG. 1 illustrates a related art laser display system.
Referring to FIG. 1, the related art laser display system is provided with a laser 10 for emitting a beam of light, a focusing device 120 for focusing the beam of light, an acousto-optic modulator (AOM) 130 for regulating transmission of the beam of light incident thereon from the focusing device 120 based on a picture signal, a polygon mirror 140 for turning, and reflecting the beam of light incident thereon from the AOM 130, to provide a horizontal image of the picture signal, a galvanometer 150 for moving up/down at a fix angle repeatedly for providing a vertical image of the picture signal, and a screen 160 for displaying the images provided at the polygon mirror 140 and the galvanometer 150.
The operation of the related art laser display system will be described.
The laser 110 emits the beam of light, and the focusing device 120 focuses the beam of light. Then, the AOM 130 regulates transmission of the focused beam of light in response to an electric signal related to the picture signal.
The polygon mirror 140 turns, and reflects the beam of light to provide the horizontal image, and the galvanometer 150 moves up/down at a fix angle repeatedly, to provide the vertical image of the picture signal. According to this, the screen 160 can display an image provided thus.
FIG. 2 illustrates a related art laser display system.
Referring to FIG. 2, the related art display system is provided with a laser 210 for emitting a beam of light, an illuminating device 220 for irradiating the beam of light to a display panel to be described later, a display panel 230 for regulating a quantity of light from the illuminating device 220 based on a picture signal, to provide an image, a projector 240 for enlarging and projecting the image, and a screen 250 for displaying the image.
The operation of the related art laser display system will be described.
When the laser 210 emits a beam of light, the illuminating device 220 irradiates the beam of light to the display panel 230. Then, the display panel 230 regulates a quantity of light based on an electric picture signal, to form a picture to be displayed. The display panel 230 is in general an LCD (Liquid Display Panel).
Thereafter, the picture formed at the display panel 230 is enlarged at the projector 240, and displayed on the screen 250.
In the meantime, a red laser, a green laser, and a blue laser are used as the laser light source, for realizing a color picture. That is, by projecting a superimposed light of red, green, and blue colors to the screen, the user can watch the color picture. The lights are superimposed by the following method in the related art.
FIG. 3 illustrates a related art light superimposer.
Referring to FIG. 3, the related art light superimposer is provided with a red laser 310, a green laser 320, a blue laser 330, first, and second filters 340, and 350 each for transmitting, or reflecting a particular wavelength.
The related art light superimposer is operated as follows.
The first filter 340 superimposes lights from the red laser and the green laser, and the second filter 350 superimposes the light superimposed at the first filter 340 with a light from the blue laser, to display the superimposed light of the three colors on the screen 360.
However, a system of the light superimposer in FIG. 3 has problems in that there is a spatial limitation in arranging the light sources, leading a size of the system large because it is required that each of the first filter 340 and the second filter 350 is arranged at 45° from a path of light without fail, and the lights from the lasers are incident on the filter at 90° with respect to each other.
That is, if the 45° arrangement of the first filter 340 and/or the second filter 350 from the path of light fails, or the light incident on the filter at 90° with respect to each other fails, transmissivity of the filters 340 and 350 changes, to have non-uniform light distribution.
FIG. 4 illustrates a light superimposer of optical fibers.
That is, referring to FIG. 4, the light superimposer is provided with a red laser 410, a green laser 420, a blue laser 430, and optical fibers 440 connected to the lasers respectively, for irradiating the color lights to the screen 450.
The light superimposer of optical fibers reduces the spatial limitation caused by arrangement of the light source, to reduce a size of the system. However, putting output surfaces of the optical fibers together exactly on one plane has been very difficult.